JPH0828310B2 - Manufacturing method of multilayer capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing a multilayer capacitor, and more particularly, to a multilayer capacitor having an improved side margin region between an internal electrode and a side surface of a dielectric. Manufacturing method.

[Conventional technology]

Multilayer capacitors are widely used in order to reduce the size and capacity of capacitors. For the multilayer capacitor, for example, as shown in FIGS. 2 (a) and 2 (b), ceramic green sheets 3 and 4 coated with internal electrode materials 1 and 2 made of conductive paste are prepared, and a plurality of them are alternately arranged. Laminated, the resulting laminate is pressure-bonded in the thickness direction and then fired,
It is obtained by forming external electrodes on the side surfaces of the sintered bodies from which the internal electrode materials 1 and 2 are drawn.

Incidentally, the internal electrode materials 1 and 2 formed on the ceramic green sheets 3 and 4 move from the first edges 3a and 4a of the ceramic green sheets 3 and 4 toward the second edges 3b and 4b. It is formed to extend. Also, each internal electrode material
1, 2 are the side edges 3c, 3d, 4 of the ceramic green sheets 3, 4
It is formed in such a width that the side margin region 5 of width x is left between c and 4d.

The side margin region 5 is provided by the internal electrode material.
This is for improving the adhesion between the ceramic green sheets located above and below 1, 2 and for preventing the internal electrode materials 1, 2 from contacting on the side surface of the sintered body after sintering. Therefore,
Conventionally, in multilayer capacitors, internal electrode materials 1, 2
It was indispensable to form the side margin region 5 having the width x on the side of.

[Technical problem to be solved by the invention]

However, when the width x of the side margin region 5 is wide, the widths of the internal electrode materials 1 and 2 are naturally narrowed, which hinders an increase in capacity. Therefore, smaller
To achieve a large capacity, the width x of the side margin region 5 is preferably small.

On the other hand, in mass production of the multilayer capacitor, as shown in FIGS. 3 (a) and 3 (b), relatively large mother ceramic green sheets 6 and 7 are prepared, and one main surface thereof has a plurality of mother inner electrode materials 8. After alternately laminating a plurality of those having formed 9, the laminated body is cut along the alternate long and short dashed lines A and B to obtain individual laminated bodies, and the individual laminated bodies are fired to obtain the individual laminated bodies. Manufactures multilayer capacitors.

However, when laminating the mother ceramic green sheets 6, 7 on which a plurality of mother internal electrode materials 8, 9 are formed, some lamination displacement has to occur, and as a result, after cutting, in each laminate The internal electrode material may be exposed on the side surface of the laminate. If the internal electrode material is exposed on the side surface of the laminated body, a withstand voltage defect or a short circuit between the internal electrode materials occurs.

Moreover, when the internal electrode material reaches the vicinity of the side surface of the sintered body even before it is not exposed, that is, in FIG. 2 (a),
In the case where the side margin region 5 in (b) is small, the adhesion strength between the upper and lower ceramic layers is not sufficient, which causes peeling after sintering.

Further, when the stacking deviation occurs, the overlapping area of the internal electrodes also becomes small, and the capacitance value may be lower than the design capacitance.

For the reasons described above, although it is preferable that the width x of the side margin region 6 is narrow, it is necessary to increase the width x more than necessary, which hinders miniaturization and large capacity. In addition, variations in capacitance and delamination tend to occur due to stacking deviation.

Therefore, it is an object of the present invention to provide a method of manufacturing a multilayer capacitor which can be further downsized and have a large capacity, has a small variation in capacity value, and has improved moisture resistance and reliability.

[Means for solving technical problems]

The present invention has a laminated dielectric in which a plurality of dielectric layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is narrower than that of the dielectric layer. Is a method of manufacturing a multilayer capacitor in which a side margin region is provided on the side of, a plurality of dielectric layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is the width of the dielectric layer. And a step of obtaining a laminated type dielectric which is the same as the above, and etching the exposed side edge of the internal electrode on the side surface of the laminated dielectric where the side edge of the internal electrode is exposed. Alternatively, a step of forming a side margin region by physically removing it, a step of heating the laminated dielectric in which the side margin region is formed, and forming an oxide film on the side edge of the internal electrode, Empty formed by the margin area A sealing member made of a synthetic resin, characterized in that it comprises a step of pressure-injection.

As the above-mentioned physical removal method, there are a reverse sputtering method in which the internal electrode material is scattered by sputtering, and a method in which the internal electrode material is moved to the outside by an electrophoretic method.

[Action]

In the manufacturing method of the present invention, the side margin region is formed by etching or physical removal after obtaining the laminated dielectric. Therefore, the width of the side margin region can be accurately formed, the overlapping area of the internal electrodes can be accurately controlled, and the capacitance variation can be reduced.

Also, an internal electrode having the same width as the dielectric layer is laminated,
Since the side margin region is formed by etching or physical removal after stacking, it is not necessary to expand the width of the side margin region more than necessary in consideration of stacking deviation. Therefore, it is possible to obtain a smaller and large-capacity multilayer capacitor.

Moreover, since the laminated body in which the internal electrodes having the same width as the width of the dielectric layer are laminated is used, the tolerance for the lamination deviation is large, so that the lamination work can be easily performed.
In addition, it is possible to obtain a multilayer capacitor having a side margin region having a minimum necessary width.

Further, in the manufacturing method of the present invention, an oxide film is formed on the side edge of the internal electrode by the above heat treatment. This oxide film can enhance the adhesion to the upper and lower ceramic layers by chemical bonding. Therefore, the bonding strength between the ceramic layers in the ceramic sintered body can be effectively increased.

Furthermore, since the sealing material is filled in the voids formed by the formation of the side margin regions, the moisture resistance and the like do not deteriorate.

[Description of Embodiments] A manufacturing method according to an embodiment of the present invention will be described with reference to FIGS. 4 to 10. This embodiment is applied to a method for manufacturing a multilayer capacitor using dielectric ceramics.

FIG. 4 is a perspective view for explaining a ceramic green sheet as a laminated body layer used in the manufacture of this example and an internal electrode material formed thereon. On the upper surfaces of the rectangular ceramic green sheets 11, 12, internal electrode members 13, 14 are formed in a film shape, respectively.

The ceramic green sheets 11 and 12 are obtained by forming a ceramic slurry mainly composed of a dielectric ceramic into the shape shown in the figure. The internal electrode materials 13 and 14 are made of Ni
Alternatively, it is configured by applying a conductive paste mainly composed of a conductive material such as Cu. As a material forming the internal electrode material, various metal materials such as Ag or Ag-Pd can be used in addition to Ni and Cu. However, it is necessary to use a material that can be etched by an appropriate etchant in the etching described later.

The internal electrode material 13 is a rectangular ceramic green sheet 11
Is formed so as to extend from one end 11a toward the opposite end 11b and not to reach the end 11b. The width of the internal electrode material 13 is the same as the width of the ceramic green sheet 11. That is, the internal electrode material 13 is formed over the entire width between the side edges 11c and 11d of the ceramic green sheet 11.

The internal electrode material 14 is configured similarly to the internal electrode material 13. However, the ceramic green sheets from which the internal electrode materials 14 are drawn out such that the internal electrode materials 13 and 14 are drawn out to the opposite side surfaces of the laminate when the ceramic green sheets 11 and 12 are stacked. 12 one edge 12
The a is located on the opposite side of the one end edge 11a of the ceramic green sheet 11.

The ceramic green sheets 11 and 12 shown in FIG.
By alternately laminating a plurality of sheets, a laminate shown in FIG. 5 is obtained.
You can get 15. In the laminated body 15, three first and second ceramic green sheets 11 and 12 are alternately laminated, and a ceramic green sheet 16 to which an internal electrode material is not applied is further laminated on the uppermost portion. .

Here, one of the three internal electrodes 13a to 13c is
On the first side surface 15a of the second inner electrode material 14a-14c
Side 15b. In addition, each internal electrode material 13a ~
13c, 14a to 14c are the third and fourth side surfaces 15c,
It is also exposed on 15d.

In addition, in the conventional example shown in FIG. 2, when the conductive paste for forming the internal electrode material 1 is applied, the surface tension of the paste causes the internal electrode material 1 to be removed as shown in FIG. 6 (a). The raised portions 21a and 21b were formed on the side edges. Therefore, when a plurality of ceramic green sheets are laminated, the thickness of the internal electrode material is not uniform, which is one of the causes of layer peeling after sintering.

On the other hand, in this embodiment, as shown in the cross-sectional view corresponding to FIG. 6B, the internal electrode material 13 extends to the entire width between the side edges 11c and 11d of the ceramic green sheet 11. Since it is formed, the thickness of the internal electrode material 13 is made uniform in the width direction. Therefore, it is possible to effectively prevent the occurrence of delamination due to the uneven thickness of the internal electrode material.

Returning to FIG. 5, the laminated body 15 is pressed in the thickness direction before the sintering so that the ceramic green sheets are brought into close contact with each other. In this case, in the laminated body 15 of the present embodiment, the internal electrode materials 13a to 13c, 14a to 14c are formed so as to extend over the entire width between the third and fourth side surfaces 15c, 15d, and therefore, as shown in FIG. VII
As shown in the schematic cross-sectional view of FIG. 7 (b) taken along the line -VII, it is possible to perform pressure bonding so that the thickness becomes uniform in the Y direction of FIG.

On the other hand, in the conventional example using the ceramic green sheet shown in FIG. 2, since the side margin region 5 is formed in advance, as shown in FIG. The thickness becomes thin in the portion Z where the margin region is formed, and the thickness of the laminated body in the portion where the internal electrode materials 1 and 2 are formed and the thickness of the side portion Z where the side margin region is formed are Delamination tends to occur on the side surface of the obtained sintered body due to the difference of.

Therefore, in the present embodiment, the invention of delamination due to such reasons can be effectively prevented in the laminated body.

Next, the laminated body 15 of FIG. 5 pressed in the laminating direction is fired to obtain a laminated dielectric sintered body. Further, as shown in FIG. 8, the first and second side surfaces of the obtained sintered body 25 are covered with resist materials 26a and 26b. This resist material 26a, 2
6b is made of a material that is not attacked by an etchant used for etching described later, and a synthetic resin such as an epoxy resin can be used as an example.

In the sintered body 25, the above-described internal electrode material is baked during firing of the ceramics, so that the internal electrode 13a
13c and 14a to 14c are formed. Note that the reference numbers of the internal electrodes will be described with the same reference numbers as those of the above-described internal electrode materials.

The internal electrode materials 13a to 13c, 14a to 14c are resist materials 26a, 2
Except for the portion covered with 6b, that is, the third of the sintered body 25,
It is exposed to the fourth side faces 25c, 25d.

Next, the third and fourth side surfaces 25c and 25d of the sintered body 25 are etched with an etchant capable of etching the material constituting the internal electrodes 13a to 13c and 14a to 14c. As the etchant, for example, a strong acid such as nitric acid can be used, but when a metal material other than Cu and Ni is used as the internal electrode material, an appropriate etchant capable of etching such metal material is used. To be

The state after etching is shown in a plan sectional view in FIG. As is apparent from FIG. 9, in the sintered body 25, two sides 32, 33 adjacent to the end edge 31 of the internal electrode 13a extended to the first side surface 25a of the sintered body 25 are formed. , Side margin area 3
It is retracted inward from the third and fourth side faces 25c, 25d so as to form 4,35 between the third and fourth side faces 25c, 25d. This is because both side edges of the internal electrode 13a are etched by etching, and
4,35 is formed.

Side margin regions are similarly formed in other internal electrodes 13b, 13c, 14a to 14c.

Further, as is clear from FIG. 10, a gap 34 is formed by etching in the portion where the side margin region is formed.
a and 35a are formed.

After the etching, the sintered body 25 is washed with water or the like to remove the etchant. However, it is difficult to completely remove the residual etchant, especially the etchant remaining in the voids 34a and 35a, only by washing with water. Therefore, in this embodiment, the sintered body 25 is then placed in a heating atmosphere to scatter and remove the residual etchant.

In addition, the above-mentioned heating may use heat given in a step of baking an external electrode described later. In that case, the removal of the residual etchant and the baking of the external electrode can be performed in the same step.

Further, the removal of the residual etchant is to prevent the internal electrode from being corroded by the residual etchant. Therefore,
A method other than heating may be used as long as the etching action can be removed. For example, if the etchant is a strong acid, the residual etchant may be neutralized by dipping in an alkaline solution.

Following the removal of the residual etchant, the resist material 26
Remove a and 26b. The resist materials 26a and 26b can be removed by mechanical polishing, a method using a chemical, or the like.

In this embodiment, since the side margin regions 34 and 35 are formed by etching, the third and fourth side surfaces of the sintered body 25 are formed.
A side margin region having an accurate width can be formed inward from 25c and 25d. Moreover, the side margin regions 34 and 35 are formed after the ceramic green sheet and the internal electrode material are laminated to obtain a laminated body.
It is not necessary to form a side margin region having an extra width in consideration of stacking deviation and the like. That is, the side margin regions 34 and 35 can be formed with a width narrower than that of the conventional example. Therefore, it is understood that a small-sized and large-capacity multilayer capacitor can be realized.

Although the internal electrode material may droop from the portion exposed on the side surface when the laminated body 15 is obtained, even if such a drooping internal electrode material is present, it is surely removed by the etching. .

Next, on the surface from which the resist materials 26a and 26b are removed, for example, Ag
A conductive paste mainly composed of is applied and baked to form a pair of external electrodes 36 and 37 as shown in FIG. The external electrode 36 includes the internal electrodes 13a to 13c and the external electrode 37.
Are electrically connected to the internal electrodes 14a to 14c.

In addition, after forming the external electrodes 36 and 37,
3, oxidation treatment is applied to the fourth side faces 25c, 25d. The oxidation treatment is achieved, for example, by subjecting the multilayer capacitor of FIG. 11 to heat treatment in an oxidizing atmosphere for a predetermined time.
In the present embodiment, the side edges of the internal electrodes 13a to 13c, 14a to 14c are arranged on the third and fourth side surfaces 25c and 25d of the sintered body 25 via the side margin regions 34 and 35 having a relatively narrow width. Since the side margin region is formed by etching, the side edge of the internal electrode is easily oxidized by the oxidizing atmosphere, thereby forming an oxide film on the internal electrode side edge. The formation of this oxide film effectively enhances the adhesion strength between the internal electrodes and the ceramics. This is because a chemical bond is generated between the dielectric ceramic and the internal electrode when it is oxidized.

Therefore, by performing the above-described oxidation treatment, it becomes possible to further improve the adhesion between the internal electrodes 13a to 13c, 14a to 14c and the dielectric ceramics.

The oxidation treatment may be performed at any stage as long as the side margin regions 34 and 35 are formed by etching. That is, the oxidation treatment may be performed prior to the formation of the external electrodes 36, 37.

Finally, the side surfaces 25c, 25d of the sintered body 25 are sealed by injecting a synthetic resin 39 such as an epoxy resin under pressure into the voids 34a, 35a in FIG. 10 as shown in FIG.

The filling of the sealing material may be performed after the external electrodes are formed, or may be performed prior to the formation of the external electrodes.
FIG. 12 is a perspective view of the multilayer capacitor filled with the sealing material. Since the voids are filled with the sealing material, the moisture resistance is not likely to deteriorate in this embodiment, and therefore, the multilayer capacitor having excellent reliability can be obtained.

Although the pair of external electrodes 36 and 37 are formed after the etching is performed in the above-described embodiment, the external electrodes may be formed prior to the etching.

In the above embodiment, since the internal electrodes 13a to 13c and 14a to 14c are made of inexpensive Ni or Cu, the electrode cost can be reduced. Further, since the mother ceramic green sheets can be laminated without paying much attention to the deviation of lamination, the manufacturing process can be simplified and the mass production cost of the laminated capacitor can be effectively reduced.

Preferably, the side surface of the sintered body on which the external electrodes 36 and 37 are formed is coated with a conductive paste mainly composed of Ni, and then the external electrodes 36 and 37 are formed.
The reliability of the electrical connection between the internal electrode and the external electrode can be improved. Further, instead of Ni, another conductive material layer may be applied to the first and second side surfaces 25a and 25b of the sintered body 25. In this case, if a material which is not etched by the etchant is used, The functions of the resist materials 26a and 26b described above can also be provided. That is, the resist materials 26a and 26b of the base electrode for forming the external electrodes can be formed. In this case,
No removal of resist material is necessary.

In the above-described embodiment, the side edges of the internal electrodes are etched using a chemical agent such as nitric acid as an etchant, but the actual etching is performed by immersing the sintered body in the etchant or in the rotating barrel. Is stored, the sintered body is put into the barrel, and the barrel is rotated.

In the embodiments described above, ceramic green sheets are used as dielectric sheets. However, the present invention is limited to a multilayer ceramic capacitor formed by laminating a plurality of ceramic green sheets and integrally firing together with internal electrode materials. is not. That is, a dielectric resin film can be used as the dielectric sheet, and the present invention can be applied to a so-called laminated film capacitor.

Further, the present invention can be applied to a winding type capacitor formed by winding a long ceramic green sheet or a resin film together with internal electrodes formed on the main surface thereof, and therefore, this type of winding It should be pointed out that the type capacitors are also included in the multilayer capacitor according to the present invention.

〔The invention's effect〕

As described above, according to the present invention, the side margin region on the side of the internal electrode is formed by etching or physically removing the side edge of the internal electrode. That is,
Since the side margin region is formed by etching or physical removal after stacking, the side margin region having the minimum necessary width can be accurately formed without considering stacking misalignment. Therefore, it is possible to obtain a small-sized and large-capacity multilayer capacitor with small variation in capacitance value.

Also, since the side margin area is formed by etching or physical removal after stacking, not only the above-mentioned small-sized and large-capacity multilayer capacitor can be obtained, but also the positioning allowable range when stacking the dielectric sheets. Therefore, the stacking work can be performed relatively easily. Further, since the internal electrode forming electrode pattern is formed to have the same width as the dielectric layer, the number of types of electrode patterns can be reduced. Therefore, the cost of the multilayer capacitor can be reduced.

Further, the edge electrode oxide film on the internal electrode side is formed by the heating step, and thereby the adhesion strength between the oxide film and the upper and lower ceramic layers is enhanced. Therefore, even when the area of the internal electrode is increased, the bonding strength between the oxide film and the ceramic layer is increased, so that it is possible to provide a highly reliable multilayer capacitor in which delamination or the like hardly occurs. It will be possible.

Furthermore, since the sealing material is filled in the voids formed by the formation of the side margin regions, there is little fear that the moisture resistance will decrease, and a multilayer capacitor having excellent reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a monolithic capacitor obtained in one embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are ceramic green sheets used for manufacturing a conventional monolithic capacitor and formed thereon. FIGS. 3 (a) and 3 (b) are plan views showing the shape of the internal electrode material to be formed, and FIG. 3 (a) and FIG. FIG. 4 is a plan view for explaining each shape, and FIG. 4 is a perspective view for explaining the shape of a ceramic green sheet as a dielectric sheet used in one embodiment of the present invention and an internal electrode material formed thereon. FIG. 5 is a perspective view showing the laminated body, and FIGS. 6 (a) and 6 (b) are cross-sectional views for explaining the shape of the side edge of the internal electrode material in the conventional example and the example. Figures (a) and (b) show FIG. 7B is a schematic cross-sectional view for explaining the shape of the laminated body after pressure bonding in the conventional example and the example, and FIG. 7B is a cross-sectional view of a portion taken along the line VII-VII of FIG. 5. , FIG. 8 is a perspective view showing a state in which a resist material is applied to the side surface of the sintered body, FIG. 9 is a plan sectional view for explaining the shape of the internal electrodes after etching, and FIG. 10 is a void created by etching. FIG. 11 is a schematic enlarged cross-sectional view showing FIG. 11, FIG. 11 is a perspective view of the multilayer capacitor before sealing material is filled, and FIG. 12 is a perspective view of a state in which the sealing material is filled in the voids. In the figure, 11 and 12 are ceramic green sheets as dielectric layers, 11a, 11b, 12a and 12b are edges, and 11c, 11d, 12c and 12d.
Is a side edge, 13, 13a to 13c, 14, 14a to 14c are internal electrode materials, 17,
19 is a mother ceramic green sheet, 18a, 18b, 20a and 20b are mother internal electrode materials, 25 is a sintered body, 25a and 25b are first and second side surfaces, 25c and 25d are third and fourth side surfaces, 26a and 26b are resist materials,
34 and 35 are side margin regions, 34a and 35a are voids, 36 and 37 are external electrodes, and 39 is a synthetic resin as a sealing material.

Claims (1)

[Claims] 1. A laminate type dielectric having a plurality of dielectric layers laminated with an internal electrode interposed therebetween, wherein the width of the internal electrode is narrower than that of the dielectric layer, whereby A method of manufacturing a multilayer capacitor, wherein a side margin region is provided on a side of an electrode, wherein a plurality of dielectric layers are laminated with an internal electrode interposed therebetween, and the width of the internal electrode is equal to that of the dielectric layer. A step of obtaining a laminated dielectric having the same width as the width, and a step of removing the exposed side edge portion of the internal electrode on the side surface of the laminated dielectric where the side edge of the internal electrode is exposed. A step of forming a side margin region by etching or physical removal, a step of heating the laminated dielectric having the side margin region formed, and forming an oxide film on the side edge of the internal electrode, Formed by the side margin region And a step of pressurizing and injecting a sealing material made of a synthetic resin into the voids.